THE CANADIAN EN^TOMOLOGIST. 121 



SO large nor so abundant. I took a number of the Como galls home with 

 me, and in due time obtained a good supply of perfect specimens of 

 T. solidaginis from them. 



The species is very fully described by Loew in his " Monograph of 

 the Diptera of North America," Part I., p. 82 (Smithsonian Miscellaneous 

 Collections, April, 1862). To those who have not access to this work, the 

 following brief description of the insect may be acceptable : — 



Size. — Expanse of wings, eleven-twentieths of an inch. Length of 

 body, six-twentieths. Width of thorax, two-twentieths. 



Head. — Face, whitish. Eyes, bronze-yellow. Antennae, yellow, short. 

 Mouth-opening wide. 



Thorax broad and convex, set with short yellowish hairs, has dark- 

 brown longitudinal stripes. Scutellum, convex and blunt. Wings, large, 

 umber-brown at the base, and then having an umber-brown, zig-zag, 

 scroll-like band ; the hyaline interstices being finely reticulated, more or 

 less, with brown. The legs are flavescent — the femora being somewhat 

 darker. 



Abdomen broad at the base, and then gradually tapering to the ex- 

 tremity — the segments being marked with short, whitish hairs. The 

 borer of the female is very distinct. It is flat, of a reddish-brown colour, 

 and tipped with black. 



The gall produced by this insect 4s a pithy gall — it is filled up with the 

 cellular tissue of the plant. Why the wounds caused by some insects 

 should produce galls of this nature, and those caused by others should 

 produce hollow galls, is one of the mysteries of Nature that science has 

 not yet cleared up. 



In the Trypeta gall, the short, plump, yellow larva lies snugly en- 

 sconsed, closely surrounded by the vegetable tissues. It gradually 

 tunnels a way of exit for the fly ; and then, as the spring draws near, 

 undergoes the pupal change. The pupa is about five -twentieths of an 

 inch long, oval, ochreous, but darkening to brown at the head. This 

 brown portion is ruptured when the fly makes its escape. 



I have raised from the galls two kinds of parasites, viz : — Eurytoma 

 gigantea, Walsh, and the males (called by Walsh, Pimpla coilebs) of 

 Pimpla inquisitor, Say. 



Eurytoma gigantea is a very remarkable insect. It is described by 

 Walsh in the 2nd Vol. of the " American Entomologist and Botanist," p. 

 300, from two females " captured at large." 



